Genetic alteration of the neurotransmitter metabolism of adrenergic CNS may play a role in the etiology of schizophrenia. The nerve growth factor protein NGF acts as a developmental and maintenance factor on these neurons. NGF has regulatory properties on catecholamine neurotransmitter synthetizing enzymes. Lower levels of NGF were measured in schizophrenic sera. We propose to quantitate the depression of NGF in schizophrenic sera. We will determine if it consists of lower levels of protein or activity and the effect of treatment on both. Use of patients suffering from depression will determine if the reduced levels of NGF are due to the schizophrenic condition or a more general attribute of patients with psychiatric problems. Use of drug free patients and controlled treatments of patients with chemotherapeutic drugs will establish the effect of such drugs on NGF levels. As part of this study we will also purify human NGF and modify our present radioimmunoassay which used antibodies to mouse NGF to one using antibodies to the beta subunit of human NGF. This will allow the determination of absolute levels of NGF in the serum samples studied.